Brothers
by Dead Man Blogging
Summary: Dr. Gaster might have taken his experiment too far. He already separated and started his tests on the eldest of the two brothers, so what more would it do to inject determination into him? Rated M for foul language, violence, and other possibly disturbing content.
1. Chapter 1

Sans sat silently in his room, a small, oddly shaped lamp lighting the colorless walls dimly. He wondered how his infant brother was doing in the other room. 'I wonder why he won't let me see Papy.' He thought sadly; Papyrus was, at that point, only about a year old.

"Sans,"

Sans quickly looked at the old metal door as it screeched open. A pale white face and dark eyes emerged from the darkness; it was Dr. Gaster.

"It's time for your tests," he said, causing a chill to immediately go down Sans' spine; his voice sounded exactly like a old computer.

"Y-yes sir," Sans sighed before pushing himself off of his worn blue bed and following.

...

The laboratory was painfully bright compared to the bedroom. Sans looked about; the walls were an almost neon white, as were the floors and every table and chair was a metallic silver. He quickly spotted a small green apple sitting on Dr. Gaster's desk.

The tall, thin Doctor grabbed the apple with his fingertips and sat it on the nearest table. "Pick it up," he commanded softly.

Sans sighed as Dr. Gaster sat in his usual chair and grabbed his clipboard. He quietly raised his arms and focused his energy on the small object.

That's when everything began to go wrong.

Sans could feel the usual pressure in the back of his head, but something seemed different; it was happening faster than usual and the pain was sharper than any time before. 'It's probably nothing,' he thought as the apple began to glow. Before the apple was even an inch off of the table, the pain shot through his body.

"Sans," Dr. Gaster's voice echoed through the room, but it was obvious that Sans wasn't listening. "Sans," he repeated with crackling force.

The apple suddenly exploded with enough force to send chunks of the core onto the far side of the room.

Dr. Gaster, unfazed, dusted the pieces of apple from his lab coat and sighed. "That's the eighteenth time this month." He said, scribbling something down on the clipboard.

In the event, Sans had dropped to the ground, his head lowered. "I'm sorry," he managed quietly, gripping his knees. "I let the pain take over again." He breathed, wiping his mouth. "Hey doc," he suddenly said, causing Dr. Gaster to look down at him.

"What is it, Sans?" He asked.

"Why do I bleed?" Sans said, looking at the blood that had dripped onto his white shirt and had gotten on his arm. "Skeletons aren't supposed to bleed."

Dr. Gaster shook his head. "All monsters bleed, Sans; you're no exception." He explained. "Again," he said, setting another apple on the table and returning to his clipboard.

Sans let out a ragged breath before standing and staring at the apple. 'I can do this,' he thought, raising his arms once again. 'I can do this, I can do this,' he repeated in his mind as he watched the apple began to move. The pain immediately returned to his temples, but he ignored it, even as the pain traveled all the way to his toes and fingertips.

Dr. Gaster watched as the apple rose slowly, a dull blue glow enveloping it almost like a blanket. "Now hold it for a minute." He said, beginning to write on the clipboard.

Sans wasn't even listening at that point; he was too focused on keeping the apple afloat.

"One minute," Dr. Gaster said loudly, finally catching Sans' attention.

"Y-yes sir," Sans groaned, his sights locked on the floating apple; the pain, at that point, was almost unbearable.

When the minute was up, blood was streaming down Sans' face, soaking his white tank top. The apple hit the table barely a moment before Sans collapsed onto the ground.

"Very good," Dr. Gaster's voice echoed emotionlessly through the room as he stood.

Sans nodded, pulling himself to his feet. "Hey doc," he coughed.

Dr. Gaster turned his head just enough to see the young monster. "What is it?"

"Can I see my baby brother now?"

Dr. Gaster sighed and gave him a big smile.

"Maybe tomorrow."


	2. Chapter 2

Dr. Gaster always said that.

'Maybe Tomorrow'

The words spun like a broken record in Sans' mind, cutting deeper each time. The inability to see his little brother hurt more than the pain the tests put him through. 'I just want my brother,' he thought, his head in his hands as he sat on his bed; Dr. Gaster had promised that he would have his brother back when the tests were over, but with each day that passed, it seemed more and more like a pipe dream than a promise.

There was a knock on the door, but Sans ignored it.

"Sans, it's time to get up," Dr. Gaster said, knocking on the door again.

"Yes sir," Sans said, his voice still raspy from the day before. He quietly stood and slipped on his slippers before walking to the door.

The door screeched open, as usual and Dr. Gaster walked in, surprising Sans; the doc never even entered the room unless he was horribly injured the day before.

"Hello, sir." Sans said quietly, shoving his hands into his pockets.

Dr. Gaster nodded, obviously not paying attention.

"Is... Is everything alright?" Sans asked, cocking his head.

Dr. Gaster once again nodded. "We're going to do something different today." He said; it was obvious his mind was wandering. "Follow me," he said before turning around and leaving the room.

Sans stood there for a moment, absolutely confused before following.

...

"Where are we going?" Sans asked, looking about; they had already walked past the laboratory

Dr. Gaster remained silent, not even bothering to look back.

Sans let out a small breath; of course he wasn't going to tell him. He never told him, so why would he say something now?

"Outside,"

Sans froze for a moment before hopping to catch back up with Dr. Gaster. "Wh-were?" He managed, obviously shocked, but Dr. Gaster had already resumed his walking.

After a few minutes of walking in complete silence, Dr. Gaster stopped at an obviously old large metal door. It didn't look very well worn, but the edges were covered in a thick layer of rust. He pressed the side of the door, causing it to drag loudly over the floor, the sound similar to the sound of nails on a chalkboard.

Sans couldn't help but cringe; the noise was worse than Dr. Gaster's voice.

Light immediately flooded through the doorway as the door hit the wall, sending an echo through the building.

"Come," Dr. Gaster said before going through the door.

Sans stood there for a moment before reluctantly following.

...

Snow was falling from above as they got outside. The ground as well as the surrounding trees were coated in the cold white powder, which made a muffled crunch as Dr. Gaster and Sans made their way out.

It had been months since Sans had been outside and the thought of such freedom actually scared him. "Wh-why are we out here?" He asked, looking over at Dr. Gaster, who was digging around in his pockets.

"You'll see in a moment." Dr. Gaster said bluntly; it was obvious that he was flustered. His face moved slightly, catching Sans' attention.

Sans always knew that Dr. Gaster was different from him. He wore a mask and never showed his true face. At first, he was quite interested in what the doctor looked like, but as the tests continued, his interest had all but disappeared.

Dr. Gaster fixed his mask as he produced a small vial from his pocket. "Here we are," he said, turning towards Sans.

Sans looked at the fluorescent blue liquid that was in the vial and couldn't help but shiver; he knew exactly what was about to be asked of him. "You want me to drink it, don't you?" He guessed, sighing deeply as Dr. Gaster nodded.

"All at once," Dr. Gaster said, handing the vial to Sans.

As Sans grabbed the vial, his hand brushed against the doctor's. A chill went down his spine; Dr. Gaster wasn't wearing his gloves and his hand was... fleshy.

Dr. Gaster immediately pulled his hand back, nearly dropping the glass vial onto the ground. He quickly took a step back and sighed. "Drink," he repeated.

Sans took a deep breath before pulling the stopper from the vial and downing it. He saw Dr. Gaster suddenly shift before his vision went blurry. A searing pain immediately tore at his insides, forcing him to his knees. "D-dammit," he groaned, gripping at his chest.

"What are you feeling?" Dr. Gaster asked; it was obvious from his voice that he was smiling.

"I-it burns," Sans managed, his words rising from his throat like acid, causing him to double over. The only relief was the cold wind blowing against the tears that were streaming down his face.

"It's supposed to," Dr. Gaster said, scribbling more notes onto his clipboard. "We will resume the tests tomorrow, as usual and you will continue to recieve these doses every morning." He explained, not even bothering to look up as Sans' cries of pain echoed through the surrounding forest. "Now let's go back inside." He said, starting towards the lab.

"Wh-why are you doing this to me?" Sans cried, clenching his jaw as he gripped the dirt and snow in his hands.

Dr. Gaster spun on his heel, slamming his foot down on the ground before picking Sans up by the front of his shirt. "You came to _me_ ," he hissed, his eyes visible from behind his mask. "I'm helping you." He said before dropping Sans on the ground and turning around. "Now come inside." He commanded, his voice like a gunshot through the cold air.

"Y-yes sir,"


	3. Chapter 3

**I'm sorry it's been so long since I've last updated; I just finished up with a long move and, in the process ended up losing my job, computer, and all my work, forcing me to start from scratch. I won't be posting very often for a while, but I'll still try to crank the chapters out as fast as I can.**

* * *

Sans couldn't think straight. His vision blurred as the morning dose was administered. He tried to shake the feeling from his head, but it was no use.

"You'll get used to it," Dr. Gaster said flatly, taking the vial before walking to the door. "I'll be back in an hour." He said before leaving the room.

As soon as the door shut, Sans curled up on the bed, gripping his head in his hands; the pain was just as bad as the first dose and it felt as if his head were about to explode? "Fuck," he mumbled under his breath, pressing his palms against his eye sockets. He could soon feel the pressure lessen and sighed. 'Why me,' he thought, tears streaming down his face. 'Why does it have to be me?'

...

Dr. Gaster entered the room without so much as a knock and sighed when he saw Sans; he had his oversized blue jacket wrapped tightly around him and his hood pulled over his face. "Sans," he said, but was slightly surprised as Sans didn't respond. "Sans," he repeated sharply, finally causing Sans to shift.

"What," Sans groaned quietly; it was obvious that he was still in a large amount of pain.

"It's time for your tests." Dr. Gaster said, ignoring the pain in Sans' voice.

Sans nodded, pushing himself off of his bed. As soon as his feet touched the ground, he pulled back.

"What is it?" Dr. Gaster asked, cocking his head slightly.

"Th-the floor," he stammered, surprised. "I-It's very cold." He murmured, wrapping his arms tightly around his torso. He looked over at his slippers snd sighed. "May I... wear my slippers?" He asked, glancing over at Dr. Gaster, who grudgingly nodded.

"As long as you don't stall any more than you already have." Dr. Gaster sighed, crossing his arms.

Sans nodded before shuffling over to the door, grabbing his slippers and pulling them on.

Even Dr. Gaster could blatantly see that something was wrong. "Let's go," he said before leading Sans out.

...

Sans looked about the room; everything was in its usual place, but something seemed...different.

Dr. Gaster walked past him and stopped at his desk. He reached around his old white desktop computer and sat a small lead weight on the table, sounding a metallic echo through the room.

Sans didn't even notice the noise, he was too focused on the subtle difference.

"Destroy it," Dr. Gaster said, once again retrieving his clipboard and pen.

Sans, hearing his words, looked over at the weight and then it clicked. He glanced about the room shocked; the tables were dirty and barren, the chairs had obviously not been moved in a while, a few lights weren't functioning, and it looked to be utterly abandoned.

"Sans," Dr. Gaster said, annoyed. "Are you listening?" He asked.

Sans could hear the grinding of what had to have been teeth and nodded. "Yes sir," he said, turning back towards the weight. "I just have to destroy it, right?" He chuckled, moving his fingers as Dr. Gaster nodded. "Then I've got this." He said, a grin plastering his face; destroying things for him was already as easy as breathing.

"Don't be too sure," Dr. Gaster said flatly.

Sans looked over at him and smiled. "How about this; if I destroy it, you'll take me to Grillby's." Sans laughed.

"And if you don't?" Dr. Gaster asked, crossing his arms.

Sans shrugged. "I'll let you decide that." He said, glancing sideways at the weight.

Dr. Gaster thought for a moment. "If you lose, your dosage will be doubled." He said, causing Sans' smile to falter. "What happened; you seemed so sure of yourself before." He said mockingly.

Sans clenched his jaw before turning back to the weight. "I still am," he said, reaching both hands out as his smile returned.

Dr. Gaster could see something change in the young monster and readied his pen.

Sans didn't even have to concentrate to lift the weight. The blue light enveloped the weight and lifted it about a foot from the table. He was honestly surprised to realize that there was no longer any pain in the back of his head. He let one of his arms drop and smiled quietly to himself as the weight remained suspended in the air.

"That's enough stalling," Dr. Gaster sighed, scribbling something down.

Sans nodded, raising his other arm back up. He immediately focused on the weight, his fingers twitching about at strange angles.

Dr. Gaster quickly turned his attention to the object as it started shaking. He suddenly flinched as the weight cracked loudly once, and then again, and again.

It took around ten seconds for the weight to explode, chunks of lead shooting out from the blue glow and impaling into the walls.

Sans soon dropped the remains of the shattered weight and looked over at Dr. Gaster, obviously proud of himself. "How was that-!" He suddenly froze when he realized that there were two large cracks in the doctor's mask. "A-are you okay, sir?!" He exclaimed, starting towards Dr. Gaster.

Dr. Gaster nodded, adjusting the mask, which caused a couple chunks to fall off around the eyes. "I'm fine," he said, looking about the room. "So I guess I owe you some lunch." He chuckled, rubbing the back of his neck.

Sans' smile immediately grew as Dr. Gaster picked up a piece of the lead weight.

"Go get changed." Dr. Gaster said as he set the piece back on the table. "I've got something I need to do and I'll come get you when I'm done."

...

Sans sat quietly on his bed, dressed in his blue jacket, slippers, and black shorts. He didn't want to get his hopes up but couldn't help but be the slightest bit excited. It had already been five minutes and Sans was starting to get slightly restless. 'Maybe he's not gonna come-!' His thought was cut short as there was a knock on the door. "C-come in." He stammered.

The door slowly opened and Dr. Gaster walked in. "You ready to go?" He asked, causing Sans' eyes to widen.

"Y-yes sir," Sans stammered, quickly trotting over to the door. He quickly noticed that the doctor's mask was still cracked.

Dr. Gaster nodded before turning and walking out, Sans close behind.

...

By the time the two departed from the grill, it was incredibly late. Most monsters were no longer out, making it easy to avoid unwanted conversations on the doctor's part.

Sans didn't realize how empty the underground had gotten until they had arrived in the forest. "Where are all the monsters?" He asked, looking up at Dr. Gaster.

Gaster merely shrugged. "Probably asleep," he sighed, glancing about the barren snowfield they had just passed through.

Even Sans could tell that the good doctor was hiding something, but he knew better than to push the conversation, instead pulling his jacket closer to his shivering body; for some strange reason, he felt more exposed to the elements than usual. 'It's probably nothing,' he thought, attempting to the best of his ability to ignore the unnerving symptoms coming to light.

The two soon re-entered the lab, which was just as cold as the snow outside.

"It's probably best if you go to bed." Doctor Gaster suddenly said, his voice unusually blunt, catching Sans off-guard.

"Ye-yes sir," Sans stammered before quickly turning and trotting off down the hall.

"It's going to be a long day tomorrow."


End file.
